/// <summary>
/// Searches for the specified item and returns the zero-based index
/// of the first occurrence within the list.
/// </summary>
/// <param name="item">The item to locate.</param>
/// <returns>
/// This returns the zero-based index of the first occurrence of the
/// <paramref name="item"/> within the list if found; otherwise, it
/// returns <c>-1</c>.
/// </returns>
/// <exception cref="item">
/// If the <paramref name="ArgumentNullException"/> is <see langword="null"/>.
/// </exception>
public int IndexOf(ReferenceVsNetItem item)
{
BuildExceptions.NotNull(item, "item");
return(_listItems.IndexOf(item));
}